Sunday, 28 February 2010

The Manchester Small-Scale Experimental Machine was the first computer to store programs in memory and was built at the University of Manchester in 1948 by Williams, Kilburn and Toothill.

The machine had 32 words of 32 bit memory, one register and supported 7 instructions:

000

JMP

s, C

Jump

100

JRP

c+s, C

Relative Jump

010

LDN

-s, A

Load and Negate

110

STO

a, S

Store

001

SUB

a-s, A

Subtract

011

CMP

Test

Skip if Negative

111

STOP

Stop

Halt Machine

With only 7 instructions the SSEM makes an ideal system for an emulation project. A basic simulator can be written in under 40 Intel x86 instructions. If you're tempted to write your own, the SSEM Reference Manual will come in handy. :-)